This invention relates to sand blasting and in particular to an improved apparatus for eliminating the dust generated from sand blasting.
In ordinary methods of sand blasting the abrasive material used scatters into clouds of dust after leaving the blasted surface. When attempts were made to eliminate this dust by using moist or wet sand and the sand was wetted before its entry into the sand blasting nozzle, it clogged the nozzle as well as the line leading to the blasting nozzle.
The prior art includes various patents pertaining to sand blasting nozzles which rely on pressurized water systems which project blanketing screens of water outside the sand jet as the jet moves from the nozzle to the surface being blasted. These systems use water volumes in the six gallon per minute range at approximately forty pounds pressure. These systems do not entirely eliminate the dust cloud. They are also unwieldy and result in costly sand blasting operations.
Included in this group are: U.S. Pat. No. 2,324,250 to J. N. Voerge which relates to a sand blast apparatus with a pressurized water system for projecting a frustro-conical stream or sheet of water around a jet of sand; U.S. Pat. No. 2,376,287 to T. Sorrentino which relates to a sand blasting nozzle provided with a removable water jacket having means to spray water about the jet of sand to settle the dust; U.S. Pat. No. 2,644,275 to J. Hoguet which relates to a water curtain projecting device for use with sand blasting apparatus; and U.S. Pat. No. 2,669,809 to J. R. McGrath which relates to a sand blasting apparatus and method which floods the surface immediately adjacent to the area of impact of sand with a continuous flood of water.
U S Pat. No. 2,440,334 to J. M. Gerlach relates to a sand blasting nozzle which draws moisture into the sand at about the area where the sand leaves the nozzle in such a way as to prevent the formation of dust without affecting the flow of sand through the nozzle. This system uses a high volume of water because of large water holes and does not provide the high degree of vacuum required to pull water from the nozzle to the object of the blast.
Accordingly, an object of this invention is to avoid the difficulties and inconveniences associated with sand blasting in the past by placing over the end of the sand blasting tool a device through which the sand jet passes and into which water is drawn. The water is drawn along the outer surface of the sand jet forming an atomized water enclosure through which the sand particles cannot travel without being wetted. The atomized water also forms a blanket of mist over the point of impact of the sand jet wetting the sand as it bounces back from the blasted surface. This wetting augments the sand's density causing the wet sand to fall down preventing its passage into the ambient air.
Another object of this invention is to provide a blanketing screen of water along the sand jet without requiring a pressurized water system.
Another object of this invention is to reduce the volume of water required to approximately one gallon per minute.
Another object of this invention is to provide the high degree of vacuum required to pull the water blanket from the nozzle to the object of the blast.
Another object of this invention is to provide a simple, light, inexpensive, convenient and durable apparatus by means of which the several objects set forth above may be accomplished.